Listeria detection · media supplement
Fraser Broth Supplement – two-component supplement
Two-component supplement for Fraser Broth Base: reagent A with the antibiotics and reagent B with ferric ammonium citrate. One set completes 225 mL of base.
- Selective supplement for Fraser Broth Base
- Lyophilised, dissolved before use
- 2 × 5 vials per box · COLO code PRO7676
How the Fraser Broth Supplement is used
Reagent A contains nalidixic acid and acriflavine, which suppress the accompanying flora. Reagent B adds ferric ammonium citrate, which reacts with the aesculin hydrolysed by Listeria and turns the broth black.
Technical data
| Composition per set | A: nalidixic acid 2.25 mg, acriflavine hydrochloride 2.81 mg; B: ferric ammonium citrate 0.1125 g |
| Use | Dissolve A in 1 mL sterile saline; add A and B to 225 mL of cooled base |
| Storage | 2–8 °C |
| Shelf life | 2 years |
Applications and practical notes
The supplement is used to complete Fraser-type broths for the enrichment of Listeria as in ISO 11290-1. Typical applications include:
- ready-to-eat foods and delicatessen
- milk and dairy products
- fish and seafood
- environmental samples from food production
Working with Fraser Broth Supplement: Dissolve the vial completely, add it only to the cooled sterile base and mix gently but thoroughly before dispensing or pouring. Keep unopened vials refrigerated.
Good practice with media and supplements: keep the bottle tightly closed in a cool, dry place, weigh the powder quickly to avoid moisture uptake, and use fresh distilled or deionised water. Check the pH of each new batch after preparation and before use, and label prepared media with the date. Performance of each lot can be verified with reference strains according to ISO 11133, the standard for the preparation, production, storage and performance testing of culture media.
About the Salmonella culture method: the reference method for Salmonella in the food chain, ISO 6579-1, has four steps: non-selective pre-enrichment, selective enrichment in two broths, plating on two selective agars and confirmation of typical colonies. The FDA BAM Chapter 5 follows the same principle with media adapted to different food types. Rapid tests and identification kits shorten the time to result, but positive screening results are usually confirmed by the culture method. COLO.Science offers products for every step, so that one supplier covers the whole procedure.
Complete sets from one supplier: COLO.Science supplies culture media, supplements, rapid tests, identification kits and QC strains as complete sets for the method you follow. Send us your sample types and standards, and we will prepare an offer with the matching products and documentation.
Fraser Broth Supplement is supplied by COLO.Science in the pack sizes listed under Ordering information. For larger quantities, regular deliveries or method-specific sets that include Fraser Broth Supplement, please send us a request. With every delivery of Fraser Broth Supplement you receive the lot number and expiry date, and on request we send the available documentation for Fraser Broth Supplement.
Where the supplement fits in the Listeria workflow
- Primary enrichment – Half-Fraser Broth
- Secondary enrichment – Fraser Broth
- Selective isolation – chromogenic Listeria agar (Ottaviani-Agosti type) plus PALCAM or Oxford Agar
- Confirmation – subculture on TSYEA, biochemical identification and latex
Ordering information
| Product | COLO code | Pack |
|---|---|---|
| Fraser Broth Supplement | PRO7676 | 2 × 5 vials |
| Fraser Broth Base, dehydrated | PRO7446 | 500 g |
| Half-Fraser Broth Base, dehydrated | PRO7536 | 500 g |
Product notice: preparation, storage conditions and shelf life are given on the label. Technical data on this page are for orientation; the label and the lot documentation apply. B2B prices are quoted net, excluding VAT.
Sales and technical support
COLO LabExperts
Polje ob Sotli 4, SI-3255, Slovenia
Quotations and technical support for culture media and microbiology products across our international sales territory. B2B prices are net, excluding VAT.
COLO.SCIENCE | MICROBIOLOGY SUPPORT
Need the complete set for your method?
Send the sample type, target organism and the standard you follow. COLO.Science will put together the media, supplements, QC strains and confirmation tests for the whole procedure.
